US5414723AExpiredUtility

Infrared laser system

60
Priority: Feb 15, 1991Filed: Feb 14, 1992Granted: May 9, 1995
Est. expiryFeb 15, 2011(expired)· nominal 20-yr term from priority
Inventors:Vladimir B. Krapchev
H01S 3/307
60
PatentIndex Score
21
Cited by
39
References
27
Claims

Abstract

PCT No. PCT/US92/01230 Sec. 371 Date Aug. 11, 1993 Sec. 102(e) Date Aug. 11, 1993 PCT Filed Feb. 14, 1992 PCT Pub. No. WO92/15137 PCT Pub. Date Sep. 3, 1992.An infrared laser system includes a neodymium laser for generating a pulsed laser beam at a wavelength of 1.06 micrometers and a Raman cell containing a Raman active medium. The laser beam, having sufficient peak power to cause emission of light from the Raman active medium by stimulated Raman scattering, is directed through the Raman cell. Ethanol-d1 or methanol-d1 is used as the Raman active medium to generate wavelengths of about 1.5 micrometers, 2.8-2.9 micrometers, or both. The laser is preferably a neodymium YAG laser.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. An infrared laser system comprising: a neodymium laser for generating a pulsed laser beam having a wavelength of 1.06 micrometers;   a Raman cell containing a Raman active medium selected from the group consisting of ethanol-d 1  and methanol-d 1  ; and   means for coupling said laser beam through said Raman cell, said laser beam having sufficient power to cause emission of light from said Raman active medium.   
     
     
       2. An infrared laser system as defined in claim 1 wherein said neodymium laser has a pulse width of 100 picoseconds or less. 
     
     
       3. An infrared laser system as defined in claim 1 wherein said laser comprises a mode-locked neodymium YAG laser. 
     
     
       4. An infrared laser system as defined in claim 1 wherein said neodymium laser has a pulse width T p  less than T B  (gG/4g B ), where T B  is the Brillouin lifetime, g is the Raman gain coefficient, G is the total integrated gain and g B  is the Brillouin gain coefficient. 
     
     
       5. An infrared laser system as defined in claim 1 wherein said neodymium laser comprises a broadband Q-switched neodymium laser having a bandwidth Γ B  of 1 cm -1  or more. 
     
     
       6. An infrared laser system as defined in claim 1 wherein said neodymium laser comprises a broadband Q-switched neodymium laser in which the wideband Brillouin gain coefficient is smaller than the Raman gain coefficient. 
     
     
       7. An infrared laser system as defined in claim 1 wherein said Raman active medium comprises ethanol-d 1  and wherein said laser beam has sufficient power to cause emission of light from said Raman active medium at 1.54 micrometers. 
     
     
       8. An infrared laser system as defined in claim 1 wherein said Raman active medium comprises ethanol-d 1  and said laser beam has sufficient power to cause emission of light from said Raman active medium at 2.79 micrometers. 
     
     
       9. An infrared laser system as defined in claim 1 wherein said Raman active medium comprises methanol-d 1  and wherein said laser beam has sufficient power to cause emission of light from said Raman active medium at 1.51 micrometers and 1.54 micrometers. 
     
     
       10. An infrared laser system as defined in claim 1 wherein said Raman active medium comprises methanol-d 1  and wherein said laser beam has sufficient power to cause emission of light from said Raman active medium at about 2.8-2.9 micrometers. 
     
     
       11. An infrared laser system as defined in claim 1 further including means for increasing the viscosity of said Raman active medium sufficiently to suppress Brillouin backscattering. 
     
     
       12. An infrared laser system as defined in claim 11 wherein said means for increasing viscosity of said Raman active medium comprises means for cooling said Raman active medium sufficiently to increase the viscosity thereof. 
     
     
       13. An infrared laser system as defined in claim 12 wherein said means for cooling is sufficient to reduce the temperature of said Raman active medium to about -50° C. 
     
     
       14. An infrared laser system as defined in claim 11 wherein said means for increasing the viscosity of said Raman active medium comprises a viscous material mixed with said Raman active medium. 
     
     
       15. An infrared laser system as defined in claim 14 wherein said viscous material comprises deuterated glycerol. 
     
     
       16. An infrared laser system as defined in claim 15 wherein said deuterated glycerol comprises about 40% by weight of said Raman active medium. 
     
     
       17. An infrared laser system as defined in claim 1 further including a viscous material mixed with said Raman active medium. 
     
     
       18. An infrared laser system as defined in claim 17 wherein said viscous material comprises deuterated glycerol. 
     
     
       19. An infrared laser system as defined in claim 18 wherein said deuterated glycerol has a concentration of about 20% to 60% by weight of said Raman active medium. 
     
     
       20. An infrared laser system as defined in claim 18 wherein said-deuterated glycerol has a concentration of about 40% by weight of said Raman active medium. 
     
     
       21. An infrared laser system as defined in claim 1 wherein said Raman cell includes an input window for receiving said laser beam, an output window and means for containing said Raman active medium between said input window and said output window, and said coupling means includes a lens for focusing said laser beam in said Raman active medium. 
     
     
       22. An infrared laser system as defined in claim 1 wherein said coupling means includes a lens for focusing said laser beam in said Raman active medium. 
     
     
       23. An infrared laser system as defined in claim 22 wherein said coupling means further includes a polarizer and Faraday rotator for isolating the laser beam from radiation that is backscattered from said Raman cell. 
     
     
       24. An infrared laser system as defined in claim 23 wherein said Raman cell further includes means for cooling said Raman active medium. 
     
     
       25. An infrared laser system as defined in claim 22 wherein said coupling means further includes means for isolating the laser from radiation that is backscattered from said Raman cell. 
     
     
       26. An infrared laser system as defined in claim 1 further including beam splitting means for separating said laser beam at 1.06 micrometers from the light emitted from said Raman active medium. 
     
     
       27. An infrared laser system as defined in claim 1 further including means for circulating said Raman active medium through said Raman cell.

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